Midwave infrared type-II InAs/GaSb superlattice detectors with mixed interfaces

We report the growth and fabrication of midwave infrared InAs/GaSb strain layer superlattice (SLS) detectors. Growth of alternate interfaces leads to a reduced strain between the GaSb buffer and SLS (Delta a(parallel to)/a=-5x10(-4)), enabling the growth of active regions up to 3 mu m (625 periods). The structural, optical, and electrical properties of the active region were characterized using x-ray crystallography and photoluminescence, respectively. p-i-n detectors were grown using 625 periods of 8 ML (monolayer) InAs/8 ML GaSb as the active region. The lambda(cutoff) for the detectors was 4.6 mu m with a conversion efficiency of 32% at V-b=-0.2 V. Detectivity was obtained using noise power spectral density measurements under 300 K 2 pi field of view illumination and was equal to 5.2x10(10) and 3x10(10) cm Hz(1/2)/W (V-b=-0.02 V, T=80 K) in the white noise and 1/f noise limit (at 50 Hz). (c) 2006 American Institute of Physics.